JPS6372715A - Production of solvent-resistant, porous fine particle of uniform-particle diameter - Google Patents

Abstract

PURPOSE:To obtain a solvent-resistant, porous fine particles of uniform particle diameter, by extracting a solvent-soluble substance from a precursor of porous crosslinked polymeric fine particles obtained by copolymerizing a crosslinking monomer mixture in the presence of swollen particles obtained by allowing specified lowly crosslinked polymeric fine particles to absorb a pore modifier. CONSTITUTION:Solvent-resistant, porous fine particles having a uniform particle diameter of 2-30mum and a standard deviation of a particle diameter distribution <=1mum are obtained by the following process. Namely, a monomer mixture comprising 99-99.5wt% noncrosslinking monomer and 1-0.05wt% crosslinking monomer is added to an aqueous dispersion of noncrosslinked polymeric fine particles of a particle diameter of 0.5-2mum and a standard deviation of a particle diameter distribution <=0.1mum, obtained by growing the particle diameter by seed polymerization, and the obtained mixture is polymerized. The obtained crosslinked polymeric fine particles are allowed to absorb a pore modifier to form swollen particles. These swollen particles are allowed to absorb a crosslinking monomer mixture, and the obtained particles are copolymerized in an aqueous medium to obtain a precursor of porous crosslinked polymeric fine particles. A solvent-soluble substance is extracted from the precursor of the porous crosslinked polymeric fine particles.

Description

Detailed Description of the Invention: Industrial Application Field The present invention provides a porous crosslinked polymer comprising non-crosslinked polymer fine particles, a pore control agent, a crosslinked polymer with a low crosslink density, and a crosslinked polymer with a high degree of B. A method for producing fine particles of uniform particle size that are 2 to 30 μm in diameter, have a standard deviation of particle size distribution of 1 μm or less, are solvent resistant, and are porous, and are characterized by removing solvent-soluble substances from a precursor of the fine particles. Regarding the manufacturing method.

BACKGROUND OF THE INVENTION Polymer fine particles used as opacifying agents, matting agents, organic pigments or fillers, thickness and gap adjusting agents, carriers for chromatography, etc. are strongly required to have uniform particle diameters. Furthermore, when used in a dispersed state in various solvents, such as when used as a thickness gap adjustment material or a carrier for chromatography, it is required that the material does not dissolve or swell in the solvent. Furthermore, in applications where a large surface area is advantageous, such as when used as a carrier for chromatography or a carrier for various substances, porous properties are also desirable.

Conventionally, as a method for producing solvent-resistant fine particles, there has been a method in which crosslinked polymer fine particles are made into sheet particles, and a non-crosslinkable monomer or a crosslinkable monomer mixture is absorbed into the sheet particles for polymerization treatment. It was known (Japanese Patent Publication No. 59-1870)
Publication No. 5, British Patent No. 728508, British Patent No. 11
No. 16800).

On the other hand, as a method for producing porous fine particles, hydrophilic vinyl monomers and acrylic acid, etc., or phenyl group-containing A method for removing the organic solvent after polymerizing a hydrophobic monomer and a hydrophilic monomer in aqueous suspension is known, as disclosed in JP-A-58-88657 and JP-A-5.
8-83260).

Problems to be Solved by the Invention However, in any of the above-mentioned methods for simply obtaining solvent-resistant particles, there is a problem in that the resulting fine particles have poor uniformity in particle size.

Further, even in the aqueous suspension polymerization method for obtaining porous materials, there is a problem that the particle size distribution of the resulting particles is wide (several microns to several tens of microns) and is poor in uniformity.

As described above, it has been difficult to obtain fine particles with excellent uniformity of particle size using conventional methods. Therefore, the current practice is to perform a classification process after polymerization to make the particle size uniform. However, classification processing has not yet been carried out so that the standard deviation of the particle size distribution is 1 μl or less in the particle size range of 2 to 30 μl.

Therefore, no method has been known to date for producing solvent-resistant, porous, uniformly sized fine particles having a particle size of 2 to 30 mm and a standard deviation of particle size distribution of 1 or less.

Means for Solving the Problems The present inventors have overcome the above problems, and the particle size is 2 to 30 μm.
We have conducted extensive research to develop a manufacturing method that allows us to obtain solvent-resistant, porous, uniformly sized fine particles with a standard deviation of one line or less in the particle size distribution without the need for classification. As a result, non-crosslinked polymer fine particles whose particle size had been grown using a sheet polymerization method were first treated with a monomer mixture containing a low concentration of crosslinkable monomers, and then added to the crosslinked polymer fine particles obtained. A porous crosslinked polymer obtained by impregnating a pore control agent to form swollen particles, and then infiltrating the swollen particles with a monomer mixture containing a high concentration of crosslinkable monomer for copolymerization treatment. The present inventors have discovered that the objective can be achieved by extracting and removing solvent-soluble substances from the precursor of fine particles, and have accomplished the present invention.

That is, the present invention includes (A) adding water and a non-crosslinking monomer to an aqueous dispersion of sheet particles, polymerizing them, and using the obtained particles as the next sheet particle to further grow the diameter. , obtained by repeating a non-crosslinked polymer obtained by treating a non-crosslinkable monomer in an aqueous medium twice or more as initial sheet particles,
The particle size is 0.5-2μ and the standard deviation of particle size distribution is 0.1μ.
99 to 99.95% by weight of a non-crosslinking monomer and 1 to 0.0% of a crosslinking monomer to an aqueous dispersion of non-crosslinked polymer fine particles of I or less.
A monomer mixture consisting of 5% by weight is added and polymerized, and a pore control agent is absorbed into the resulting crosslinked polymer fine particles to form swollen particles. A step of absorbing a monomer mixture consisting of 50 to 90% by weight of polymer and 50 to 10% by weight of crosslinkable monomer, and copolymerizing this in an aqueous medium to obtain a precursor of porous crosslinked polymer fine particles. ,(
B) A step of extracting a solvent-soluble substance from the precursor of the porous crosslinked polymer fine particles obtained in the above step, with a particle size of 2 to 3
The present invention provides a method for producing fine particles of uniform particle size that are solvent resistant and porous and have a standard deviation of particle size distribution of 1 u- or less at 0 μι.

In the method of the present invention, first, non-crosslinked polymer fine particles obtained by a sheet polymerization method are treated with a monomer mixture containing a low crosslinking monomer concentration, and pores are adjusted in the crosslinked polymer fine particles obtained. After absorbing the agent to form swollen particles, the swollen particles are made to absorb a monomer mixture containing a high concentration of crosslinkable monomers, and this is copolymerized to form a precursor of porous crosslinked polymer fine particles. obtained (Step A).

In this case, the non-crosslinked polymer fine particles are obtained by repeating sheet polymerization twice or more, have a particle size of 0.5 to 2u+a, and have a standard deviation of particle size distribution of 0.1μ or less, preferably 0.05μ.
s or less is used. That is, water, a non-crosslinking monomer, and, if necessary, an emulsifier in an amount necessary to stabilize the reaction (preferably so that the surface tension is 55 dynes/inertia or higher) are added to the aqueous dispersion of sheet particles. ) and a polymerization initiator, polymerization treatment is performed, and the obtained particles are used as the next sheet particle to further grow the diameter. The operation is repeated two or more times to obtain a predetermined size. As the initial sheet particles, a non-crosslinked polymer obtained by treating a non-crosslinkable monomer in an aqueous medium is used. That is, for example, a non-crosslinked polymer in an emulsion obtained by processing a non-crosslinkable monomer by a conventional emulsion polymerization method or the like is used.

By using non-crosslinked polymer fine particles that satisfy these conditions, the standard deviation of the particle size and particle size distribution in the final target product can be achieved.

The non-crosslinked polymer fine particles described above are subjected to treatment with a monomer mixture containing a low concentration of crosslinkable monomers. That is, the non-crosslinked polymer fine particles contain 99 to 99.95% by weight, preferably 99.5 to 99.95% by weight of the non-crosslinkable monomer in the aqueous dispersion.
．． A monomer mixture consisting of 9% by weight and a crosslinkable monomer of 1 to 0.05% by weight, preferably 0.5 to 0.1% by weight is added, and this is absorbed into non-crosslinked polymer fine particles to polymerize. It is processed to form cross-linked polymer fine particles. This makes it possible to swell with a monomer mixture containing a high crosslinking monomer content or its constituent monomers to be used later. In addition, it is possible to obtain a final target product that generally has excellent sphericity. The swelling degree (the volume ratio of the particles before and after swelling) of the crosslinked polymer fine particles obtained using the monomer mixture having the above-mentioned mixing ratio is usually 4 to 150. A material with a swelling degree of this level, preferably a swelling degree of 8 to 100, is preferred in the method of the present invention. Therefore, if the content of the crosslinkable monomer in the monomer mixture used in the above treatment is too low, a product with an excessive degree of swelling will be obtained, and the solvent resistance of the final target product, uniform particle size fine particles, will be reduced. On the other hand, if the content of the crosslinkable monomer is too high, the degree of swelling (excessive crosslinking density) will be obtained, which will be used later. The monomer mixture cannot be sufficiently diffused into the particles, resulting in insufficient polymerization in the particles, and new particles are likely to be generated, which causes variation in particle size. difficult to achieve.

The amount of the monomer mixture used in the treatment for converting the non-crosslinked polymer fine particles into crosslinked polymer fine particles is not limited, but is 2000 parts by weight per 100 parts by weight of the non-crosslinked polymer fine particles. It is preferably at most 1000 parts by weight, especially at most 1000 parts by weight. If the amount used is excessive, the resulting crosslinked polymer fine particles may have a wide particle size distribution, and the object of the present invention may not be achieved.

Note that when adding the monomer mixture to the aqueous dispersion of non-crosslinked polymer particles, it should be noted that the monomer mixture is easily absorbed into the non-crosslinked polymer particles (
It may also be added as an emulsion. In this case, it is more preferable to use an oil-soluble polymerization initiator dissolved in the monomer mixture.

Based on the monomer mixture (non-crosslinked polymer fine particles are modified with a crosslinked polymer having a low crosslink density), the crosslinked polymer fine particles are a monomer mixture with a high concentration of crosslinkable monomers. That is, the pore-adjusting agent and the monomer mixture are absorbed into cross-linked polymer fine particles, and then copolymerized in the presence of a polymerization initiator. As a result, a crosslinked polymer with a high crosslinking density based on a monomer mixture with a high concentration of crosslinking monomer and pore adjustment are obtained, as a modified crosslinked polymer fine particle having a crosslinked polymer with a low crosslinking density. A precursor of porous crosslinked polymer fine particles having an agent at least inside and having an expanded particle size can be obtained, and a final target product having a large specific surface area can be obtained.

The process of obtaining swollen particles by absorbing a pore-adjusting agent into cross-linked polymer fine particles involves adding a pore-adjusting agent to a dispersion of cross-linked polymer fine particles, especially an aqueous dispersion as an emulsion polymerization liquid, and making it into an emulsion. A method in which the agent is added and stirred is preferred. According to this method,
This has the advantage that the amount of the pore control agent absorbed into the crosslinked polymer fine particles can be easily controlled, and the monomer mixture added later can be absorbed smoothly at a high absorption rate. Of course, the method for obtaining swollen particles is not limited to the above, and any method may be used as long as the pore-adjusting agent is absorbed and swollen particles are formed as a result.

Note that during the absorption treatment, heating may be performed to increase the absorption rate, or a water-soluble solvent such as acetone or ethanol may be added.

The crosslinked polymer fine particles, which have become swollen particles by absorbing the pore control agent, are then made to absorb a monomer mixture containing a high concentration of crosslinkable monomers.

A preferable treatment method is to add an emulsified monomer mixture to a dispersion of swollen particles.

The amount of monomer mixture used is 100% of crosslinked polymer fine particles.
100 to 3000 parts by weight per part by weight is suitable.

If the amount used is less than 100 parts by weight, the solvent resistance of the resulting uniform particle size particles will be insufficient, and if it exceeds 3,000 parts by weight, polymerization outside the crosslinked polymer particles will tend to proceed (this is preferable). do not have.

The appropriate mixing ratio of the non-crosslinkable monomer and the crosslinkable monomer in the monomer mixture is 50 to 90% by weight of the non-crosslinkable monomer and 50 to 10% by weight of the crosslinkable monomer. .

If the mixing ratio of the crosslinkable monomer exceeds 50% by weight, the crosslinking density of the crosslinked polymer will be too high, and if it is less than 10% by weight, the crosslinking density will be too low, making it difficult to achieve the object of the present invention.

In the present invention, the monomer in the non-crosslinking monomer for obtaining non-crosslinked polymer fine particles, or the monomer mixture for obtaining the precursor of crosslinked polymer fine particles or porous crosslinked polymer fine particles is , those which themselves or their polymers are poorly soluble or insoluble in water are preferably used. If the material is easily soluble in water, polymerization will proceed in water, making it difficult for the particle size of sheet particles to grow, making it easier to form new particles, or increasing the crosslinked polymer content in non-crosslinked polymer fine particles. This is not preferable because it may be difficult to absorb into molecular fine particles.

Examples of non-crosslinkable monomers that can be preferably used include styrene monomers such as styrene, methylstyrene, and ethylstyrene, butyl acrylate, butyl methacrylate,
Examples include acrylic acid and methacrylic acid ester monomers having an alkyl group having 4 or more carbon atoms, such as 2-ethylhexyl acrylate and 2-ethylhexyl methacrylate.

Examples of crosslinkable monomers that can be preferably used include monomers having two or more ethylenic double bonds, such as trimethylolpropane trimethacrylate, diethylene glycol dimethacrylate, and divinylbenzene.

The number of non-crosslinkable monomers and crosslinkable monomers may be one, or two or more.

Determined according to the intended use of the object. For example, when used as a thickness gap adjustment material or a carrier for chromatography, pressure resistance is required. It is preferable to use divinylbenzene, which has low solubility, as the crosslinking monomer. The styrene monomer also has the advantage of not agglomerating during the copolymerization process (the process can proceed stably).

The appropriate amount of the pore regulator used is 100 to 6,000 parts by weight per 100 parts by weight of the crosslinked polymer fine particles. In general, it is determined based on the monomer mixture with a high concentration of crosslinkable monomer used, and although it varies depending on the type of monomer, it is usually 10 to 350% by weight, preferably 10 to 350% by weight based on the monomer mixture. 50-250% by weight is suitable. If the amount used is less than 10% by weight, the pores formed may be too small, resulting in the resulting uniform particle size fine particles having poor porous properties; if the amount used exceeds 350% by weight, pores may be formed. In some cases, the pores formed become too large, and the inside of the resulting fine particles of uniform particle size becomes hollow, resulting in a hollow substance. Therefore, from the viewpoint of porosity, pore control agents that are undesirable include solvents that can be used in the subsequent extraction process. A removable substance is used as the dissolved substance. Generally, those having a solubility in water of 1% by weight or less at room temperature (water-insoluble) and soluble in the non-crosslinkable monomer and/or crosslinkable monomer used are used. If the solubility exceeds IIt%, it may remain in the aqueous medium without being absorbed into the crosslinked polymer fine particles, and may not contribute to the formation of porosity or inhibit the stability of the reaction system. There is.

Specific examples of pore control agents include saturated hydrocarbons such as hexane, heptane, and isooctane, aromatic hydrocarbons such as toluene, xylene, and ethylbenzene, and n-hexyl alcohol, n-octyl alcohol, and 2-ethylhexyl alcohol. Examples include linear polymers such as alcohols, polystyrene, and liquid paraffin. Only one type of pore adjusting agent may be used, or two or more types may be used in combination.

The copolymerization treatment for obtaining a precursor of porous crosslinked polymer fine particles can be carried out using an appropriate medium under usual polymerization treatment conditions. When using an aqueous medium, a common oil-soluble radical initiator is preferably used as the polymerization initiator.

If it is water-soluble, new particles may be generated, which may cause problems. Note that it is preferable to use the oil-soluble polymerization initiator dissolved in the monomer mixture in an amount of 0.1 to 5% by weight in order to smoothly carry out the polymerization in the crosslinked polymer fine particles.

Incidentally, during the copolymerization treatment, it is desirable to stabilize the particles using an emulsifier or a polymerization stabilizer.

It is appropriate that the amount used is such that no new particles are generated other than the precursor of the porous crosslinked polymer fine particles.

By carrying out the copolymerization treatment as described above, particles having a structure having a pore control agent and a crosslinked polymer with a high crosslink density inside the crosslinked polymer fine particles have a particle size in the range of 2 to 30, preferably 2.
~20 μm, the standard deviation of the particle size distribution is 1 n or less, preferably 0.5 μm or less, and a precursor of porous crosslinked polymer fine particles that generally has excellent sphericity can be obtained. Note that the crosslinked polymer having a high crosslinking density in the precursor of the porous crosslinked polymer fine particles may be chemically bonded to the precursor,
It is also possible to have a crosslinked polymer with a high crosslinking density on the surface of the precursor of the porous crosslinked polymer fine particles.

In the method of the present invention, the precursor of the porous crosslinked polymer fine particles obtained in the above step is then subjected to a step of extracting a solvent-soluble substance (Step B). As a result, uniform particle size particles can be obtained, which are made of crosslinked polymer particles imparted with porosity. These uniformly sized fine particles generally have excellent mechanical strength.

Extraction of solvent-soluble substances can be performed, for example, by the following method.

That is, water as a dispersion medium in the aqueous dispersion containing the precursor of porous crosslinked polymer fine particles obtained in the above step A is gradually replaced with a less polar medium, and the non-crosslinked monomer used is Finally, the polymer or its polymer is replaced with a medium having a similar SP value (solubility parameter) to that of the pore control agent, and washing is repeated with this medium to make the precursor of the porous crosslinked polymer fine particles soluble in the solvent. Extract the substance.

As the substitution medium, it is generally desirable to use a volatile low boiling point solvent, since it is ultimately desired to remove it from the fine particles. Typical examples include alcohols such as methanol and ethanol, ketones such as acetone, acetonitrile, chloroform, tetrahydrofuran, benzene, toluene, xylene, and ethylbenzene. The displacement medium may be a hot medium containing water or a hot medium using 2 parts 1 or more of a solvent.

In some cases, it is efficient to carry out the extraction process by dispersing the precursor of the porous crosslinked polymer particles in a replacement medium. In that case, it is also possible to apply a dispersion method using ultrasonic waves, for example.

Note that the substitution medium remaining in the porous crosslinked polymer fine particles after the extraction treatment can be easily removed by, for example, a vacuum drying method, a spray dryer, or the like.

As described above, the particle size is 2 to 30 μm, preferably 2 μm.
~201, the standard deviation of the particle size distribution is 1 micron or less, preferably 0.5 micron or less, and excellent solvent resistance and porous uniform particle size can be obtained. These uniform particle size particles generally contain a cross-linked polymer with a high cross-link density inside a cross-linked polymer with a low cross-link density, and are composed of cross-linked polymer particles having a huge separate porous structure, and have a specific surface area of 30J. /g or more, preferably 50 to 1000+J/g, more preferably 100 to 5007/g, and has excellent sphericity and mechanical strength.

In addition, it is also possible to use an ion exchange resin or the like as the uniform particle size fine particles having a functional group such as an ion exchange group.

Effects of the Invention According to the present invention, non-crosslinked polymer fine particles with excellent particle size uniformity are first made into crosslinked polymer fine particles having a crosslinked polymer with a low crosslink density, and then a pore control agent is absorbed into these fine particles. This method allows the swollen particles to be made into swollen particles, and then allows the swollen particles to absorb a monomer mixture containing a high concentration of crosslinking monomers, making it possible to control the absorption of the pore control agent into the crosslinked polymer fine particles. It is easy to use, and the monomer mixture added later can be smoothly absorbed. Since this method removes the particles, it is possible to obtain uniform-sized fine particles with excellent particle size uniformity in a state that can be used for practical purposes without classification treatment, and in a high yield. has excellent solvent resistance and a large specific surface area due to its porosity.

Examples Reference Examples Sodium lauryl sulfate 0.6 parts (parts by weight, the same applies hereinafter)
30 parts of styrene was dispersed in 65 parts of ion-exchanged water in which 30 parts of styrene was dissolved, and the temperature was raised to 70°C under a nitrogen stream while stirring, followed by ion-exchanged water in which 0.03 part of potassium permate was dissolved. 5 parts were added and maintained at 70° C. for 8 hours to obtain an aqueous dispersion of a non-crosslinked polymer as initial sheet particles. The particle size of this non-crosslinked polymer was 0.045 u, and the standard deviation of the particle size distribution was 0.01 ha+ or less.

Next, 10 parts of the aqueous dispersion of the obtained initial sheet particles and 65 parts of ion-exchanged water were mixed, heated to 70°C, 27 parts of styrene was added and stirred for 1 hour, and then 0.1 parts of potassium persulfate was added. Add 5 parts of ion-exchanged water and heat to 70°C.
An aqueous dispersion of secondary sheet particles having a particle size of 0.162 μm and a standard deviation of 1 particle size distribution of 0.014 μm was obtained. Further, in accordance with the above procedure, tertiary sheet particles were prepared from secondary sheet particles, quaternary sheet particles from tertiary sheet particles, and 5th sheet particles from quaternary sheet particles with the compositions shown in the table.

Example 1 The quaternary sheet particles obtained in Reference Example were used as non-crosslinked polymer fine particles, and 100 parts of ion-exchanged water and 10% by weight of polyvinyl alcohol with a degree of saponification of 88% were added to 10 parts of an aqueous dispersion as a preparation liquid. After adding 5.0 parts of an aqueous solution and stirring uniformly, 99.85 parts by weight of styrene and 0.0 parts of divinylbenzene were added.
0 benzoyl peroxide in 16 parts of a 15% by weight monomer mixture.
．． 2 parts were dissolved, 120 parts of ion-exchanged water and 0.015 parts of sodium lauryl sulfate were mixed thereto, an emulsion was added under ultrasonication, and the mixture was heated under a nitrogen stream for 8 hours while stirring.
Polymerization was carried out at 0° C. for 8 hours to obtain an aqueous dispersion containing crosslinked polymer fine particles. The particle size of this crosslinked polymer fine particle is 1
．． 217n, standard deviation of particle size distribution is 0.060 IJl
The degree of swelling with respect to styrene was 11.

Next, 50 parts of ion-exchanged water and 5 parts of the above-mentioned polyvinyl alcohol aqueous solution were added to 12 parts of the obtained aqueous dispersion of crosslinked polymer fine particles and stirred uniformly. A mixture of 100 parts of ion-exchanged water and 0.012 parts of sodium lauryl sulfate was added to make an emulsion under ultrasonic treatment, and 10 parts of acetone was added as an absorption promoter, and the mixture was stirred at room temperature for 24 hours to form a crosslinked system. An aqueous dispersion of swollen particles consisting of fine polymer particles was obtained.

Next, 16.8 parts of a monomer mixture of 65% by weight of styrene and 35% by weight of divinylbenzene and 0.8 parts of benzoyl peroxide were dissolved in this aqueous dispersion, and 1 part of ion-exchanged water was added to this.
30 parts of sodium lauryl sulfate and 0.012 parts of sodium lauryl sulfate were mixed together and treated with ultrasonic waves to make an emulsion. The mixture was heated to 55°C under a nitrogen stream for 2 hours with stirring, and then heated to 80°C for 6 hours.
A time copolymerization treatment was performed to obtain an aqueous dispersion containing a precursor of porous crosslinked polymer fine particles. The particle size of this precursor is 3.2 On,
The standard deviation of the particle size distribution was 0.15n.

Next, the dispersion medium in this aqueous dispersion was changed from water to methanol, ethanol, acetone, acetone/toluene (1/1
) and toluene to prepare a toluene dispersion, which was then heated at its boiling point temperature for 40 hours. Thereafter, fine particles were separated from the toluene dispersion and further washed with toluene, and then the dispersion medium was replaced in the reverse order to prepare an aqueous dispersion.

The extracted porous crosslinked polymer fine particles were separated from the obtained aqueous dispersion and dried under reduced pressure.

The obtained porous crosslinked polymer fine particles with a uniform particle size had a particle size of 3.20 μm and a standard deviation of particle size distribution of 0.15 μm, which was the same as that of the precursor described above. . In addition, the weight loss of the fine particles after the extraction treatment, that is, the weight loss of the uniform diameter fine particles as the porous crosslinked polymer fine particles obtained by the extraction treatment with respect to the precursor of the porous crosslinked polymer fine particles is 40%. %Met.

Furthermore, B, E.

The specific surface area determined by the T method (nitrogen gas adsorption) is 205
．． It was 6j/g. Furthermore, as a result of observation using a scanning electron microscope, it was found that in addition to being porous, it also had excellent sphericity.

Example 2 The 5th sheet particles obtained in Reference Example were used as non-crosslinked polymer fine particles, and 100 parts of ion-exchanged water and the above polyvinyl alcohol aqueous solution 5 were added to 10 parts of an aqueous dispersion as a preparation liquid.
After stirring uniformly, 0.2 parts of benzoyl peroxide was dissolved in 16 parts of a monomer mixture of 99.85% by weight of styrene and 0.15% by weight of divinylbenzene, and 120 parts of ion-exchanged water was dissolved therein. , sodium lauryl sulfate 0.0
15 parts were mixed and an emulsion was added under ultrasonic treatment, and the mixture was polymerized at 80°C for 8 hours under a nitrogen stream while stirring.
An aqueous dispersion containing crosslinked polymer fine particles was obtained. The particle size of the crosslinked polymer fine particles was 2.41 parts, the standard deviation of the particle size distribution was 0.12 uss, and the degree of swelling with respect to styrene was 12.

Next, 25 parts of ion-exchanged water and 3 parts of the above-mentioned polyvinyl alcohol aqueous solution were added to 5 parts of the obtained aqueous dispersion of crosslinked polymer fine particles, and the mixture was stirred uniformly. A mixture of 50 parts of ion-exchanged water and 0.006 parts of sodium lauryl sulfate was added to make an emulsion under ultrasonic treatment, and 5 parts of acetone was added as an absorption promoter, and the mixture was stirred at room temperature for 24 hours to form a crosslinked system. An aqueous dispersion of swollen particles consisting of fine polymer particles was obtained.

Next, 8.4 parts of a monomer mixture of 65% by weight of styrene and 35% by weight of divinylbenzene and 0.4 parts of benzoyl peroxide were dissolved in this aqueous dispersion, and 65% of ion-exchanged water was dissolved in this aqueous dispersion.
1 part and 0.006 part of sodium lauryl sulfate were mixed together to make an emulsion under ultrasonication, and the mixture was copolymerized at 55°C for 2 hours under a nitrogen stream with stirring, and then heated to 80°C for 6 hours. An aqueous dispersion containing a precursor of porous crosslinked polymer fine particles was obtained. The particle size of this precursor was 6.80 μm, and the standard deviation of the particle size distribution was 0.28 μm.

Next, extraction treatment and drying treatment were carried out in the same manner as in Example 1 to obtain porous crosslinked polymer fine particles.

The obtained porous crosslinked polymer fine particles with a uniform particle size had a particle size of 6.78 μm and a standard deviation of particle size distribution of 0.28 μm, which was almost the same as that of the precursor described above. Ta. Furthermore, the weight reduction of the fine particles after the extraction treatment was 38%.

Further, the specific surface area determined by the B, E, T method (nitrogen gas adsorption) was 112.8j /g. Furthermore, as a result of observation using a scanning electron microscope, it was found that in addition to being porous, it also had excellent sphericity.

Example 3 25 parts of ion-exchanged water and 3 parts of the above polyvinyl alcohol aqueous solution were added to 5 parts of an aqueous dispersion of the same crosslinked polymer particles as in Example 2, and after uniform stirring, 70 parts of n-hexyl alcohol was added. % by weight and 30% by weight of toluene (precipitating/swelling agent N0 parts, ion-exchanged water 50 parts)
A mixture of 0.006 parts of sodium lauryl sulfate and 0.006 parts of sodium lauryl sulfate was added to make an emulsion under ultrasonic treatment, and 5 parts of acetone was added as an absorption enhancer, and the mixture was stirred at room temperature for 24 hours to form crosslinked polymer fine particles. An aqueous dispersion of swollen particles was obtained.

Next, 8.4 parts of a monomer mixture of 65% by weight of styrene and 35% by weight of divinylbenzene and 0.4 parts of benzoyl peroxide were dissolved in this aqueous dispersion, and 65% of ion-exchanged water was dissolved in this aqueous dispersion.
1 part and 0.0013 parts of sodium lauryl sulfate were mixed together to form an emulsion under ultrasonic treatment, and the mixture was copolymerized at 55°C for 2 hours under a nitrogen stream with stirring, and then heated to 80°C for 6 hours. An aqueous dispersion containing a precursor of porous crosslinked polymer fine particles was obtained. The particle size of this precursor is 6.78 μm1
The standard deviation of the particle size distribution was 0.29μ.

Next, extraction treatment and drying treatment were carried out in the same manner as in Example 1 to obtain porous crosslinked polymer fine particles.

The obtained porous crosslinked polymer fine particles having a uniform particle size had a particle size of 6.78 μm and a standard deviation of the particle size distribution of 0.29 μm, which was the same as that of the precursor described above. Furthermore, the weight reduction of the fine particles after the extraction treatment was 41%. Further, the specific surface area determined by the B, E, T method (nitrogen gas adsorption) was 161.27 parts g. Furthermore, as a result of observation using a scanning electron microscope, it was found that in addition to being porous, it also had excellent sphericity.

Example 4 The 5th sheet particles obtained in Reference Example were used as non-crosslinked polymer fine particles, and 100 parts of ion-exchanged water and the above polyvinyl alcohol aqueous solution 5 were added to 10 parts of an aqueous dispersion as a preparation liquid.
After stirring uniformly, 0.2 parts of benzoyl peroxide was dissolved in 16 parts of a monomer mixture of 99.85% by weight of styrene and 0.15% by weight of divinylbenzene, and 120 parts of ion-exchanged water was dissolved therein. , sodium lauryl sulfate o, o
The ts part was mixed and an emulsion was added under ultrasonic treatment, and the mixture was polymerized at 80°C for 8 hours under a nitrogen stream while stirring.
An aqueous dispersion containing crosslinked polymer fine particles was obtained. The particle size of this crosslinked polymer fine particle is 2.41ules, the standard deviation of the particle size distribution is 0.12μ11, and the degree of swelling with respect to styrene is 1
It was 2.

Next, 25 parts of ion-exchanged water and 3 parts of the above-mentioned polyvinyl alcohol aqueous solution were added to 5 parts of the obtained aqueous dispersion of crosslinked polymer fine particles, and the mixture was stirred uniformly.
10 parts of ion-exchanged water, and 0.006 parts of sodium lauryl sulfate were mixed to form an emulsion under ultrasonication, and 5 parts of acetone was added as an absorption promoter, and the mixture was stirred at room temperature for 24 hours. An aqueous dispersion of swollen particles made of crosslinked polymer fine particles was obtained.

Next, 8.4 parts of a monomer mixture of 65% by weight of styrene and 35% by weight of divinylbenzene and 0.4 parts of benzoyl peroxide were dissolved in this aqueous dispersion, and 65% of ion-exchanged water was dissolved in this aqueous dispersion.
1 part and 0.006 part of sodium lauryl sulfate were mixed together to make an emulsion under ultrasonication, and the mixture was copolymerized at 55°C for 2 hours under a nitrogen stream with stirring, and then heated to 80°C for 6 hours. An aqueous dispersion containing a precursor of porous crosslinked polymer fine particles was obtained. The particle size of this precursor was 6.82 μm, and the standard deviation of the particle size distribution was 0.32 μm.

Next, extraction treatment and drying treatment were carried out in the same manner as in Example 1 to obtain porous crosslinked polymer fine particles.

The obtained porous crosslinked polymer fine particles having a uniform particle size had a particle size of 6.82 μm and a standard deviation of the particle size distribution of 0.32 μm, which was the same as that of the precursor described above. Further, the weight reduction of the fine particles after the extraction treatment was 40%. Furthermore, the specific surface area determined by the B, E, T method (nitrogen gas adsorption) is 310.9j
/g. Furthermore, as a result of observation using a scanning electron microscope, it was found that in addition to being porous, it also had excellent sphericity.

Claims (1)

[Claims] 1. (A) Water and a non-crosslinking monomer are added to an aqueous dispersion of sheet particles and polymerized, and the resulting particles are used as the next sheet particle to further grow the diameter. The operation was repeated two or more times using a non-crosslinked polymer obtained by treating a non-crosslinkable monomer in an aqueous medium as initial sheet particles, and the particle size was 0.5 to 2.
A non-crosslinking monomer of 99 to 99 mm is added to an aqueous dispersion of non-crosslinked polymer fine particles having a standard deviation of particle size distribution of 0.1 μm or less in μm.
A monomer mixture consisting of 95% by weight and 1 to 0.05% by weight of a crosslinkable monomer is added and polymerized, and a pore control agent is absorbed into the resulting crosslinked polymer fine particles to form swollen particles. After that, 50 to 90% by weight of non-crosslinkable monomer is added to the swollen particles.
a step of absorbing a monomer mixture consisting of 50 to 10% by weight of a crosslinkable monomer and copolymerizing it in an aqueous medium to obtain a precursor of porous crosslinked polymer fine particles; (B) the step described above; The particle size is 2 to 30 μm and the standard deviation of the particle size distribution is 1.
A method for producing fine particles having a uniform particle size of .mu.m or less, solvent resistance, and porosity. 2. The method according to claim 1, which uses an emulsifier. 3. The method according to claim 1, wherein the pore regulating agent is insoluble in water and soluble in the monomer mixture or its constituent monomers. 4. 100 to 6000 parts by weight of a pore regulator and 50 to 10 parts by weight of a crosslinkable monomer per 100 parts by weight of crosslinked polymer fine particles.
The method according to claim 1, wherein the monomer mixture containing 100 to 3000 parts by weight is used. 5. The method according to claim 1, wherein the monomer mixture containing 50 to 10% by weight of the crosslinkable monomer contains a polymerization initiator. 6. Adding a pore regulator in an emulsified state to an aqueous dispersion of crosslinked polymer particles 7, and a monomer mixture containing 50 to 10% by weight of a crosslinking monomer in an emulsified state of the swollen particles. The method described in Section 1.